Head or gasket?

[nsh95]

Getting a miss fire as I hit boost and the exhaust seems to smell of coolant.. Not smoking terribly bad, 1 or 2 on a scale to 10.. Any ideas?

[19jdog]

Is the coolant reservoir getting low?

[nsh95]

Not driving it currently parked. Not seeming to be burning a lot. Light light smoke just enough to notice, but it's miss firing anytime it gets around 5k rpms.

[audi_nightrider]

What kind of coilpacks do you have installed?

[customa4]

This^^ If there's no other symptoms except misfires under high load, definitely check the coilpacks. First thing to do is pull the codes from the car and post them. If there's a misfire on cylinder 1, swap that coilpack with cylinder 2 and then take the car for a spin and see if the misfire follows the coilpack. If the misfire stays on the same cylinder after swapping coilpacks around you'll want to follow the same procedure with the fuel injectors.

There was a recall for the coilpacks on our cars. It'd be worth giving the dealership a call with your VIN number to see if your car still needs the coilpacks replaced under the recall. It's free if the recall wasn't done.

[nsh95]

I have one 2.0 coil pack (EDIT: one 2.0 the other three are 1.8 packs) in the cylinder that seems to look clean like it's been steam cleaned by the coolant on that cylinder so to speak.. Should I replace that 2.0 coil pack with a 1.8 and see if that fixes the issue?

[old guy]

You smell coolant in the exhaust?

You are noticing a light smoke from the exhaust?

You have one plug that looks steam cleaned?

I think you have already answered your own question.

You can try the coil pack/injector swap just to confirm but it sure sounds like a head gasket issue.

[nsh95]

So is there any definitive way to determine if the head gasket is toast or if the head is warped/cracked..? What sort of repairs am I to expect to be performing now?

[old guy]

It would really help to pull the DTC's as suggested by Customa4 to determine the cylinder causing the misfire. It it corresponds with the spark plug that looks steam cleaned that would point in the direction of a bad head gasket.

Next try moving the coil pack and injector from the misfiring cylinder to another cylinder and see if the misfire remains with original misfiring cylinder or if it moves with the swap.

Assuming it remains with the original cylinder there are two additional tests you can perform to confirm a bad head gasket. You can go to your local AutoZone and rent a compression leak gas test and see if there are any combustion gasses in the coolant.

The other test would be a leak down test on the cylinder in question. Again, you can probably rent the equipment from AutoZone. Pressurize the suspect cylinder with the coolant reservoir cap removed. Look for changes in the coolant level or bubbles in the coolant. Either condition would indicate a head gasket leak.

Good luck!

[nsh95]

Awesome, thanks OG always helpful!!!

[diagnosticator]

Awesome, thanks OG always helpful!!!

1.8T cylinder heads that have small crack between the valve seats, cannot leak coolant into the cylinders. It is simply impossible. Audi advises that as long as the cracks are less than ~0.8 mm wide, the head can be reconditioned and used without any reason to be concerned about the cracks.

I don't know of any confirmed occurrences of 1.8T cylinder heads actually developing a crack that was capable of leaking coolant into the cylinders.